Pharynx is a conical fibromuscular tube forming upper part of air and food passages.

Divisions:Nasopharynx Oropharynx Hypo/laryngopharynx. Structure of Pharyngeal wall. From outwards:4 layers Mucous membrane Pharyngeal aponeurosis Muscular coat Buccopharyngeal fascia.

Extension: Plane of hard palate above to the plane of

hyoid bone below. Lies opposite to the oral cavity with which it

communicates thro’ oropharyngeal istmus. Boundries of istmus:Above:soft palateBelow:upper surface of tongue.Either side:palatopharyngeal arches.

Posterior wall:related to retropharyngeal spaces and lies opposite to the 2nd and upper part of 3rd cervical vertebrae.

Anterior wall:deficient above where oropharynx communicates with oral cavity but below

(a)Base of tongue:posterier to circumvallate papillae

(b)Lingual tonsils:one on either side situated on base of the tongue.

(c) Valleculae:cup shaped depression lying b/w the base of the tongue and anterior surface of epiglottis.

Each is bounded medially by the median glossopharyngeal fold and laterally by pharyngoepiglottic fold.These are seat of retention cyst.

Lateral wall:(a)Palatine tonsil(b)Anterior pillar formed by palatoglossus muscle.(c)Postreior pillar formed by palatopharyngeus

muscle. Both the anterior & posterior pillar diverge from

soft palate & encloses triangular depression called Tonsillar fossa where tonsil is situated.

Oropharynx Jugulo digasic node. Soft palate,lateral & posterior

pharyngeal walls and base of the tongue

retro and para pharyngeal nodes

jugulodigastic and posterior cervical groups.

Base of the tongue bilaterally

As a conduit for passage of food and air. Helps in the pharyngeal phase of deglutition. Forms part of vocal tract for certain speech

sounds. Helps in appreciation of taste:taste bubs

present on the base of tongue,soft palate,anterior pillars &post pharyngeal walls.

Provides local defence & immunity.

Two in number. Each is ovoid mass of lymphoid tissue

situated in the laterel wall of oropharynx b/w the anterior & posterior pillars.

Actual size is bigger than that appears from the surface as tonsil extends upwards into the soft palate,downwards into the base of the tongue &anteriorly into the palatopharyngeal arch.

Tonsils have: Two surfaces:medial & lateral. Two poles:upper and lower.

Medial surface:covered by st.sq.non keratinised epithelium which dips into the surface of tonsils as crypts.

Openings of 12 to 15 crypts can be seen on the medil surface of tonsils.

One of them in the upper part of the tonsil is very large & deep & called as Crypta Magna/Intra tonsillar cleft which represents the ventral part of 2nd pharyngeal pouch.

From the main crypts arise secondary crypts within the substance of tonsils.

Crypts may be filled with cheesy material consisting of epith cells,bacteria & food debris which can be expressed by the pressure over anterior pillar.

Lateral surface:presents a well defined fibrous capsule.

B/w the tonsil & the bed of the tonsil is the areolar tissue which makes it easy to dissect the tonsil in the plane during tonsillectomy.

Also the site for collection of pus in peritonsillar abscess.

Some fibres of palatoglossus &palatophartngeal muscles are attached to the capsule of the tonsil.

Upper pole:extends into the softpalate. Its medial surface covered by semilunar fold

extending b/w anterior & posterior pillars & enclosing a potential space called supratonsillar fossa.

Lower pole:attached to the tongue.A triangular fold of mucous membrane extends from anterior pillar to antero inferior part of tonsil & encloses a space called anterior tonsillar space.

The tonsil seperated from the tongue by sulcus called tonsillolingual sulcus which may a seat of carcinoma.

Bed of the tonsil:Formed by superior constrictor & styloglossus

muscle. The glossopharyngeal nerve & styloid process if

enlarged may lie in relation to the lower part of tonsillar fossa.so both these structures can be surgically approached thro’ tonsil bed after tonsillectomy.

Outside the superior constrictor,tonsil is related to the facial artery,submandibular salivary gland,posterior belly of digastic muscle,medil pterygoid muscle & the angle of mandible.

5 arteries: Tonsillar branch of facial artery:Main artery. Ascending pharyngeal artery from external

carotid artery. Ascending palatine a branch of facial artery. Dorsal lingual branches of lingual artery. Descending palatine branch of maxillary artery.

Venous drainage:tonsillar vein:paratonsillar vein:common facial vein:pharyngeal venous plexuses.

Lymphatic drainage:Lymphayics from tonsil Deep

cervical nodes particularly jugulodigastic nodes below the angle of mandible.

Nerve supply:lesser palatine branches of sphenopalatine ganglion(5th CN) & glossopharyngeal nerve provide sensory nerve supply.

Protective role & act as sentinals at the portal of air & food passages.

Crypts:increase the srface area for contact with the foreign substances.

Tonsils are larger in childhood 7 gradually dicrease in size by the time of puberty.

Removed when themselves become seat of infection.